Yeah, I've had the same problem with my Heritage '84. I laundered the bag when I got it about three years ago, and I never could get the original em-tor back on. My cat even tried to help (see my avatar photo, taken while I was trying to put that machine back together), but to no avail. I apparently lack the "reasonable strength and skill" necessary for that task. In the end, I simply gave up and substituted a Heritage II style mini em-tor, which has been on it ever since.
Over the years, I've gone back and forth about swapping the original em-tor and fill tube assembly back on that machine. My plan when I got the machine was to keep it looking original and use up the small supply of Style 2 bags I have on hand, but that plan got sidetracked the day I got it. As it is now, it works quite well, and it occupies the same bag ecosystem as all my other Kirbys. The extended part of my original plan, once I ran out of Style 2 bags, was to keep the original em-tor in place, but swap a Heritage II style fill tube topper onto the assembly to allow it to use the same bags as everything else.
One of these days, maybe...